Rectifier Short or Grounded & Stator Grounded Test

Fig. 14 Side Terminal Alternator Rectifier Short Or Grounded & Stator Grounded Test:

Fig. 15 Rear Terminal Alternator Rectifier Short Or Grounded & Stator Grounded Test:

Fig. 16 Alternator w/Integral Regulator Rectifier Short Or Grounded & Stator Grounded Test:

Using a suitable ohmmeter, connect one probe to the alternator BAT or B+ terminal, Figs. 14, 15 and 16, the other probe to the STA terminal (rear blade terminal). Then, reverse the ohmmeter probes and repeat the test. A reading of about 6-6.5 ohms should be obtained in one direction and no needle movement with the probes reversed. A reading in both directions indicates a bad positive diode, a grounded positive diode plate, grounded BAT or B+ terminal or a shorted radio suppression capacitor, if equipped.
Perform the same test using the STA and GND (ground) terminals of the alternator. A reading in both directions indicates either a bad negative diode, a grounded stator winding, a grounded stator terminal, a grounded positive diode plate, or a shorted radio capacitor, if equipped.
Infinite readings (no needle movement) in all four probe positions in the proceeding tests indicates an open terminal lead connection inside the alternator.